Spring clutch construction



Jan. 25,1927. Y 1,615,804

w. c. S TARKEY SPRING CLUTCH CONSTRUCTION Filed March 22 1926 1'13). 1 ya A TTORNE Y.

an la-a, 1921.

spring which engages the recess walls.

UNITED "STATES PATENT OFFICE.

wmux CA RLETON STABKEY, OF INDIANAPOLIS, INDZ IAN A, ASSIGNOB 1'0 L. G. B.

nnvlcns conroaarron puma.-

, OI INDIANAPOLIS,

, spams om rrcn cons'rnuc'riou;

Application filed mun a2, 1926. Serial No. 96,374.

This invention is concerned with a clutch of the type in which two relatively rotatable co-axial members, areprovidedwith alined circular recesses for the reception cat a c011 Such a clutch is shown in United States Letters Patent No. 1,006,500 issued to Erick B. Peterson on October 24, 1911. 'In such a clutch the spring operates to clutch the two i members together when they tend torotate 5 spring recedes slig relatively in a direction to unwind the spring; and when the two members rotate relatively in the opposite direction, a tcnd- [ency-to wind the s ring is produced and the tly fromthe recess walls and permits free rotation in that direction.

It is the object of my invention to cheapen and simpli y the manufacture of such a clutch. A further object of my invention 90 is to make the clutch more ,POSltlVG in operation by insurin "the coil spring that all the turns of wil operate to clutch the two relatively rotatable members together when the tend to rotatein a direction to;

p unwind t e. sprin 80 fore placing'the-spring in the recess, 1

. will prevent an I accomplish the above objects by pro viding near the bottom of each sprm -reannular groove slig tly than the recess, and be- PIQL clutch meinber with'means which spring-turn from entering such groove. o-msure-thatall the turns of the'coil spring cooperate in the clutchceiving recess an larger in diameter vide each ing function, I construct each groove-closing means so as to provide one or more abutments adapted to'be en aged by the adjacent spring-end, and I %end each end-turn of-the spring axially outward so that the spring-end may yield sufficiently to permit relative .rotation of the spring and clutch member in a direction to wind the spring. The accompanying drawing illustrates 'my invention: Fig. ,1 is a longitudinal central s ction through .a clutch provided with one form of groove-closing means; Fig. 2 i's' va. longitudinal central section through one of the clutch members with the spring removed; Fig. 3 is a cross-section on the line.

3-3 of Fig. 1; Fig. 4 illustrates the split spring 'ring which forms the groove-closing means shown in Fig. 1; Fig, 5 is a longitudinal section through a clutch member provided with a modified form of split with a difierent,

members spring ring; Fig. 6 is a transverse section on the line 6-6 ofFig. 5; Fig. 7 is a longitudinal section ofa clutch member provided form of grooye-closing section on the line 8-8 means; Fig. 8 isa 1s a longitudinal section or Fig; 7; Fig. 9

INDIANA, A CQBYOMTIOH OF IN- of a clutch member provided with a still different form of groove-elosing means;

elevation'of the groove-closing Fig. 10 is an means shown in section .in Fig. 9; and Figs. 11 and 12 are fragmental longitudinal sections illustrating a modified form of coil spring. v f

'I have illustrated my clutch as applied to two co-axial shafts of my clutch is not limited to this specific situation, as it may be used to interconnect any two. relatively rotatable, co-Iaxial parts.

'The shaft 10 is provided at its end with 10 and 11, but the use.

a clutch member 12, and .the shaft 11 is i provided with a clutch member, 13. .The

two clutch members 12 and .13 are" recessed tor the reception of a coil spring 14, which is preferably of such a diameter as to bearlightly against the c a recesses, although it may be of less diameter than .the recesses.

Some convenient means is employed for preventingaxial separation of the two'clutch members 12 and 13. Tothi's'end, I have illustrated the, clutch member 13 as being counter-bored to receive the clutcln member ylindrical' walls of the 12 and as extending over and be 0nd such clutch member. In the innersur ace of the clutch member 13 -I provide an annular groove for the reception of a spring rin 15, which, when in place bears against the ack of the clutch member 12 and holds the two clutch members together.

In the manufacture of a ,clutch ofthe type herein described, it is desirable that the sprin -engaging surf-ace of the clutch e ground in order to provide a suitable bearing for the spring. Such grinding has heretofore been an expensive and troublesome'operation because of the difficulty experienced in obtaining the necessary sharp corner at the bottom'of the re cess- It is possible to overcome this difficulty by undercutting the recess wall to form a groove 16 as shown in Fig. 2 of the drawing, but the presence of this groove the completed-clutch is a disadvantage 1n that the end turn otthe coil spring drops ment-bet-weg the cylindrical surfaces of and after the grinding is finished I .each clutch member means for preventinginto the groove and tends to become wedged therein. v

To eliminate these difliculties I provide each clutch member with the annular groove 16 to provide clearance for the grinding wheel which. is used to finishthe recesswalls,

' any of the spring turns from entering the space "to expand to fill the groove 16! When in groove the ends of-the ringplace in the. 17 are spaced apart. as is evident from F1 3 and the dottedlines of Fig. 4. The stoc from which the ring 17 is made is of suf ficient width so that the internal diameter 14 axially outward, as illustrated in of-the ring when it is, in place will be materiall lessthan the diameter of the recess innor er that the ring may form a shoulder against which the adjacent end of the coil spring may abut.

-Preferab1y- I bend each end of the gpring 1g. 1,

so that whe'n the two clutch members 12 and .13 tend to rotate relativelg tion to unwind the spring eac 7 spring '"end will project axially outward into the gap between the ends of the adjacent ring 17 ends and willbe engaged by one of-sueh ring andthe adjacent sp'ring-end-prevents relative rotation of the springl i and the clutch member's-and insures that the spring will beunwoundfrom'its ends to bring all of 1 its turns into firm engagement with the recess walls of the clutch members;

In' order to illustrate g the construction more clearly the" outward.- bending of the ends of the ring 14 has been'exaggerated. This outwai 'd bending need only be sufii- .cient to -'permit the spring-ends to' move axially inward to permit free relative rotation of the two clutch members in a directiontending to wind the spring.

Thespring ends and their associated spring rings 17 form what are in effect ratchet-devices .which operate to -'prevent relative rotation of the spring 14 and the clutch members '12 and 13 when thetwo transmitted clutch members tend to. rotate in a direction to unwind the spring. In accomplishing this result, the spring-ends transmit only a very sinall roportion of the total torque between the two clutch. mem-- i-bersas ractically the entire torque is transmitted, yreason oi. the frictional engaggmount in ina direc- This engagement between each-ring e' 23 servetransmitted directly between the spring 14 sp' g and the recesses. The slight forceandthe rings17 serves merely to insurethat- .thespring '14: will unwind from its ends to bring all its turns into firm engagement with the walls of the associated. recesses when "the two clutch -members tend to retate relativelyin a direction to unwind the splring. Another means for. accomplishing t 's sameresult is shown in the co-pending application of Albert Lieber, Serial No. 71,281, filed November 25, 1925.

The ring 17 shownin Figs. 1, 3, and 4 should be somewhat less in'thickness than the width of the groove 16 which it occupies in order to insure that it will be free to expand into such groove. Its thickness, however, should closely a proximate the width of such groove in or er that it may have no axial movement when in place in the clutch member. This precise regulation of the thickness of the ring 17; is apt to be expensive, and'I therefore prefer to use the ring 20 shown in Figs. 5 and 6, which. ring eliminates the necessity for careful control of either the thickness of the ring or the width of the groove 16. The ring 20 is somewhat thicker than the width. oi; the groove 16 and one outer edge (if-the ring is beveled sufiiciently to makethe circumfer- "ential face offthe'ring slightly'less in width than the width of the groove 16. When the ring20 expands into the groove l6.its bev-. eled face engages the bottom edge of the ground cylindrical surface ofthe'recess. in

the clutch member as is clear-from'Fig- 5; i For this tgpe of ring to be effective, its. expansion s ould be limited by the-engagement of the beveled .face with theibottom edge of the'cyliiidrical recess-rather than by the engagement oftthecircumferential.

ring surfacewith' the bottom of the groove 16.:- The-ring'QO' has an advantage over the Ion ring 17 that'the-outward force it exerts against the clutch member 12 servesfto hold it in a definite axial-position relative to such clutch inember, and this result is. a'cconiplished without the necessity .fj'ir closely relatin i the thickness of the ring-20 and the wi th of'the groove 16.

*InFigs. 7Land8, 'I-have illustrated a oove closing means which is difierent rom thetwo forms of bove described and is as effective; This groove-closing means consists of a'disk 22 which has a thickness greaterithan the width of the groove-16. The disk 22- is of such a diameterthat it is a press fitin the recess in the clutch member 12' and vhence when in place is rigid with such" clutch member. .One or more notches 23 may bepro'vided in the periphery of the'disk '22 in position to be entered by the out-bent adaoent springsend. The sides of the-notches m the same purpose, in respect,

split spring ring circumferen'tial series of teet formed by striking up pors ring-enga whic out" its working length,

spring 14 so that t e spring with each clutch member is secured by reason of the frictional engagement member is preferable,

flbe anything I desired.

- together.

.to 6 .inc usive such as do the ends of the that they spring and the clutch members in a direction tending to unwind the spring.

In Figs. 9 and 10 I have illustrated a stilldiiierent type of groove closin means. This consists of a disk 25' rovide witha 26 which may rings 17 and 20 in conveniently be tions of the disk 25 as indicated n the drawing. The disk 25, when formed, is dished. as indicated in Fig. 9. This dishingof the disk-25 reduces its diameter so that it can be placed at the r bottom of the recess in the clutch member and then flattened andexpanded to fill the groove 16. The teeth 26 on the disk 25 servethe same purpose as do the sides of the notches 23 'in the' disk 22. The disks 22and 25 have an advantageover the split spring rings 17 and 20- particularly notlcea e'xle when the spring M has a normal ternal diameter less than the diameter of the recesses in the clutch members. When such a spring is used, the plurality of 'ng abutments provided by the i'sks 22 an 25 lessen the distance through which'the two clutch members'must be'rotated in a direction to unwind the spring before they are clutched together. i

By the use of the 'roove-closing means described I am enable -to grind the recess ineach of the clutch members so that such recess will have the same diameter through-v and I avoid the inconvenience attendant upon the use of a clutch. member havin an annular groove in which the spring-en may become wedged. In the device which I have shown-and de scribed each of the clutchmembers is provided with a recess for the reception of the operative connection of ofthe sprin with the walls of the recess. in such clutc member. While this manner of interconnecting the sprin'g with the clutch it is only necessary that the spring be so connected to one-of such clutch members as its mode of 0 connection to the other clutch mem er may The springs in clutches of the general t pe herein described may be so roportioned as to transmit a predetermine maximum torque in the directionv in which they operate to clutch the two shafts 1 0 and 11 A A clutch equipped with such a spring when subjected to a torque ater than the predetermined maximum will slip and ermit relative rotation of the two parts itconnects. It will tation of one of the rings 16 or 20 in its as-v prevent relative rotation of thethe dotted lines in era'tive' be obvious that -in the t pe of clutch. illustrated in Fi s. 1

slippagejwillflentai ro- P sociated clutch member. normal diameter of the groove-closing rings, and thus varying the .force 'with which they bear against their associated clutch members, the maximum torque which a given transmit can be controlled to When this maximum torque is exclutch can an extent.

'ceeded, one of the grooveclosing rings rotates withthe .s ring relative to the clutch member in whic i it is located. The grooveclosing means illustrated in Figs. elusive are not adapted to rotate relative to their associated clutch'members, as the are pressed into such clutch. members an are practically rigid therewith. If it is desired to .use such groove-closing means with a By varying the I 7 tov 10 inspring which may slip when subjected toa torque greater than a-predete'rminedj'orque,

the spring-end, or the abutment which it engages, or both, maybe beveled as indicated in order-that the force in Figs. 11 and 12 transmitted between the spring-end and its associated abutment will have a component axially' of the clutch.. This component of force, inthe normal operation of the clutch, 4

is exceeded by the axial resiliency of the last spring-turn, and the. spring-endtherefore remains in engagementlwith' its abutment; but when a maximum predetermined torque is exceeded, this axial component of 'force overcomes last spring turn and'forces-the spring-end inward to permit 'the spring and clutch member to rotate relatively in the direction tendin to unwind the spring.

I cla1m as my invention 1. In combination, two relatively rotatable coaxial members having alined circular recesses, a coil spring located injsaid' recesses and having contact with each of said members'so that when-they tend to rotate relatively in a direction to unwind said spring 'it' will expand into firm frictional engagement with the walls of its associated re cesses-tg prevent such relative rotation, each of said clutchmembe'rs being-provided with an annular groove of its .recess near the bottom thereof, and means for preventing any of the turns of said spring from entering said grooves.

.2. In co coaxial members havingalined circular re.- .cesses,- a coil spring lo'catedin said recesses and-having. contact with each of said memhere so that when they tend to rotate relatively in a direction to; unwind said spring it will expand into firm-frictional engagement with the walls of its associated recesses .to revent such relative rotation, ea h of sai clutch members being annular. groove in-the cy its .recess 'near ndrical wall of the axial resilience of the Y moi in' the cylindrical wall bination, two relatively rotatable I the bottom thereof, and a split spring ringlocated in .saidgroove to revent a spring turnfrom entering it.

. 3. Incombination, tworelatively rotatable members, one of said members having an axial cylindrical recess, a coil spring cated in said recess and having an operative connection with the other of said rotatable members, said spring having contact with said recessed member so that when saidmembers'tend to rotate in a direction to unwind said spring it will expand into firm :trictional engagement with the wall of such recess to prevent such rotation, said recessed clutch member being provided with ah annular groove in the cylindrical wall of its recess near the bottom thereofi and means for preventing any of the turns of said spring from enteringsaid groove; g

4. In c0mbination,fwo relativel rotatable members, one of said members aving' an axial cylindrical recess, a coil spring located in said recess and havingan'operative connection with the other of said rotatable members, said spring having contact with said recessed. member so that when said members tend to rotate in a direction to unwind said spring it will expand into firm frictional engagement with the wallof such recess to prevent such rotation, said recessed clutch member being provided with an annular groove in the cylindrical wall of its recess near the bottom thereof, and a split spring ring located in said groove to prevent a sprung turn from entering it.

5. In combination, two relatively rotatable members, one of said members having an) axial cylindrical recess, acoil spring located in said recess and having an operative con nection with the other of said rotatablemembers, said spring having contact with said recessed member so that when saidmembers-tend to rotate in a direction to 1mwind said spring it will expand into firm frictional engagement with the wall of such recess to prevent such rotation, said recessed clutch member being provided with an annular groove in the cylindrical wall'of its ble members, one of a spring turn from entering recess near the bottom thereof, and a split spring ring located in said groove to prevent-- it, said ring ex?- tending' radially inward beyond the recess wall to form tin/abutment for the. adjacent end of said s ring.

' 6. The com inationset forth in'claim 5'- with the additioirthat the ends of said split 1 spring ring are spaced apart when said'ring the end of said coil spring being entering the spacebetween the ends of said.

"7. In combinatiomtwo relatively 'rotata said' members having an axial cylindrical recess, a-coil spring'lo cated in said recess and having an operative connection with the other of said rotatable members, said spring having contact with said recessed member so that when said members tend'to rotate in a direction to 7 f 11. In combination,

unwind said spring it will expand firm I frictional engagement with the wallofsnch wsaid-two members rotate in a direction t5 wind said spring. Y

8. In combination, .two relatively rotatm ble members, one of said members having an axial cylindrical recess,.a coil spring 10- cated in said recess and having an operative connection with the other of said rotatable members, said spring having contact with said recessed member so that when said members tend to rotate-in a direction to unwind said springit will expand into firm frictional engagement with the wall of such recess toclutch said two members together,

and an abutment normally rotatable with said recessed member and in position to engage the adjacent end of said spring when said two members rotate in a direction to unwind .said spring, said spring-end being bent so that it can recede t?) permit the passage or said abutment when said two members rotate in a direction to wind said spring.

9., In combination,- ble members, one of said members having an axial cylindrical recess, a coil spring located in said "recess and having an operative connection with the other of-said rotatable members, said spring having contact with said "recessed member so that when said members tend to rotate in.' a direction to unwind said spring it will expand into firm frictional engagement with the wall ofsuch recess to clutch said two members together, and an abutmentnormally rotatable with;

said recessed member and m'positionto en-i gage the adjacent end of said spring, said abutment and said spring-end f arranged to oppose relative rotation 0 said spring and said recessed member when they two relatively rotata- 10. The combination setfforth in claim-7 with the additionthat said abutmentand the spring-end it i-engages have engaging faces oblique tothe' spring axis.-;--

two relatively rotatable members, one of said members having an axial cylindrical recess,'a ocoil spring located in said recess and having anoperative connection with the other of said rotatable members, said spring, ha contact wan :said recessed member so't 't. when-saidmembers tend to rotate i i a. directionwto my. I

unwind said spring it will expand into firm frictional engagement withthee wall of such recess to clutch said and means acting near the end of said spring 5 for normally opposing relative rotation'of said spring and said recessed member in a direction to unwindsaid spring, said means acting to permit relative rotation of said two members together,

spring and clutch member in such direction when a giver! torque between them is ex- 10 seeded. n

In witness whereof, I have hereunto set my hand at Indianap01is,- Indiana, this 11th day of March, A. D. one thousand nine hundied and twenty-six.

GARLETON STARKEY. 

